San Marcos, CA Noise Ordinances: Vehicle Noise (2026)
Key Facts
- Horn rule
- Only permitted as a danger warning
- Engine repair window
- 7:00 a.m. to 10:00 p.m. exempts racing/adjustment
- Assessment method
- Officer's direct, unenhanced hearing and sight
- Available defense
- State-compliant horn, siren or muffler equipment
- Penalty
- Infraction under § 1.12.010; treated as public nuisance
Summary
San Marcos names unnecessary horn use and loud motor vehicle noise as violations of its noise ordinance under Municipal Code Section 10.24.020(b)(1)-(2), covering tire screech, unnecessary engine racing, backfiring, and excess muffler or exhaust noise. A violation is an infraction under Section 10.24.050, enforced by an officer's direct hearing and sight of the source.
(1)Horns and other signaling devices. The sounding of any horn or signaling device on any automobile, motor vehicle or any other vehicle on any street or public street except as a danger warning; the creation by means of any such signaling device of any unreasonably and unnecessarily loud or harsh sounds; the sounding of any such signaling device for an unnecessarily or unreasonably long period of time; or the use of any horn, whistle or other device operated by engine exhaust.(2)Motor vehicle noises. Any loud or annoying noise made by any motor vehicle and not reasonably necessary to the operation thereof under the circumstances, including, but not limited to, noise caused by screeching of tires; racing or accelerating the engine, except in the course of repair or adjustment thereof between the hours of 7:00 a.m. and 10:00 p.m.; backfiring the engine; or the emission of exhaust from the engine tail pipe or muffler.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 14 Update 1).
Full Breakdown
010. Paragraph (1) covers horns and other signaling devices: sounding a horn except as a danger warning, creating unreasonably loud or harsh sounds with a signaling device, sounding one for an unreasonably long period, or using a horn or whistle operated by engine exhaust. repair window, backfiring, or exhaust emitted from the tailpipe or muffler. 070(F). 030 sets how an officer must assess the sound: detection must rely on normal, unenhanced hearing, and the officer must get a direct line of sight and hearing to the vehicle to confirm the source and distance before enforcing.
040 allows a defense where the noise came from causes beyond the violator's control unless a curable defect went unrepaired, where the noise prevented injury to persons or property, or where it came from equipment such as a horn, siren or muffler installed and operated to meet State law requirements. 010, declares it a public nuisance the City Attorney can move to abate, and extends joint and several responsibility to a property or vehicle's owner, tenant, lessee, manager or agent who knows or should know of the ongoing noise.
Violations & Fines
Sounding a horn other than as a danger warning, racing or backfiring an engine outside the 7:00 a.m. to 10:00 p.m. repair window, or running a vehicle with excess exhaust or muffler noise violates Section 10.24.020(b)(1)-(2), an infraction under Section 10.24.050 enforced through Section 1.12.010. The vehicle's owner, lessee or a non-driving responsible party can also be cited if previously warned in writing and the noise continues.
Frequently Asked Questions
Can I be cited for honking my horn in San Marcos?
Is revving my engine to fix my car considered illegal noise?
How does an officer decide my exhaust is too loud?
Is there any defense to a vehicle noise citation?
Sources & Official References
Other rules in San Marcos
California rules heatmap·Compare San Marcos to another location·View the California noise ordinances overview
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